Growth promotion and protection of lentil (Lens esculenta) against herbicide stress by Rhizobium species

This study was designed to recover lentil-specific rhizobial strains tolerant to herbicides (quizalafop-p-ethyl and clodinafop) and synthesizing plant growth regulators even in the presence of herbicide stress. Furthermore, the impact of rhizobial strain was assessed on lentil plants grown in herbicide-treated soils. Quizalafop-p-ethyl- and clodinafop-tolerant Rhizobium sp. isolate MRL3 recovered from the nodules of lentil produced plant growth-promoting substances in substantial amount both in the absence and presence of herbicides. In addition, each herbicide at recommended, two and three times the recommended dose adversely affected lentil growth in pot trials. Both herbicides at recommended and higher rate generally decreased biomass, symbiotic properties, nutrients uptake and seed yield of lentil. Interestingly, the herbicide-tolerant Rhizobium isolate MRL3, when used with any concentration of the two herbicides, significantly increased the measured parameters compared to the plants grown in soils treated solely (without inoculant) with the same individual treatment of each herbicide. The present findings suggest that the rhizobial isolate MRL3 endowed with multiple properties could be used to facilitate the productivity of lentil under herbicide-stressed soils.